The following article features coverage from the American Society of Clinical Oncology 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Researchers from the National Cancer Institute are currently enrolling patients onto a phase 2 study combining the anti-PD1 drug nivolumab with tadalafil, and vancomycin.

Eligible patients must have refractory primary hepatocellular carcinoma (HCC) or liver-dominant metastatic cancer from colorectal or pancreatic cancers.

“Treatment options for advanced HCC and liver dominant metastatic disease from colorectal or pancreatic cancers are limited with poor overall survival,” explained M. Cecilia Monge, MD, MPH, of the National Cancer Institute in Bethesda, Maryland, and colleagues in a poster presented during the ASCO20 Virtual Scientific Program.

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The 3 drugs were selected in order to evaluate the synergy of antitumor effect induced by their combination. Tadalafil has been shown to increase antitumor immunity by decreasing myeloid-derived suppressor cells and impair tumor growth in preclinical models. Oral vancomycin affects bile acid metabolizing gut commensal bacteria leading to increased CXCL16 expression in the liver resulting in natural killer T-cell mediated liver-selective antitumor effects.

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The researchers will analyze paired liver tumor biopsies for genomic analysis, immune cell infiltration, proteomics and metabolomic studies and chemokine expression. Stool samples will also be analyzed for microbiota. In addition, blood samples will be examined to look at immune monitoring, cytokine profiles, and pharmacokinetics of the combination of the study drugs.

Treatment will include administration of nivolumab on day 1 of cycle 1 at a dose of 480 mg. Tadalafil will be given daily at 10 mg starting on day 1 of cycle 1. Vancomycin 125 mg will be given every 6 hours for a total daily dose of 500 mg. Vancomycin will be given for 3 weeks on and 1 week off.

Currently, the study has enrolled 8 patients of a planned 27.

Read more of Cancer Therapy Advisor‘s coverage of the ASCO 2021 meeting by visiting the conference page.


Monge MC, Xie C, Mabry-Hrones D, et al. Phase II study of nivolumab (anti-PD1), tadalafil, and oral vancomycin in patients with refractory primary hepatocellular carcinoma or liver dominant metastatic cancer from colorectal or pancreatic cancers. Presented at: ASCO20 Virtual Scientific Program. J Clin Oncol. 2020;38(suppl):abstr TPS4656.